Insulating a SS flue: foil wrap or pour in mix??

I am planning to insulate my 6" rigid SS liner,installed inside an exterior chimney 12"x12" clay flue liner. The idea is to improve draft as much as possible and I'm debating between using 1" insulation wrap or pouring in an insulation mix intended for this application. I want to maximize the insulation's total "R" value so that I get the best bang for my buck and labor.

The problem is that I cannot find "R" value for any products on any websites for either the wrap or the mix. My guess is I would get better insulation by filling the entire void with mix. The best I can find is that most 1/2" wrap is listed to zero clearance, and most mix at 1" is listed for zero clearance. Filling the entire void would give me more insulation even if the wrap had twice the "R" value.

Any thoughts out there or is everybody hibernating for the Summer??

I did mine with rock wool insulation, (rotten cotton) . I shoved some up from the bottom & then dropped little pieces from the top till full.
I believe it is the correct product for the job.
I did it about 20 years ago and its been working fine. I have a 8 inch liner though.
doug

I'll bet the Rock Wool is an inexpensive alternative I hadn't considered. It might be hard to get it snugged up all the way around the liner compared with a wrap or mix,though.

One thing is for certain, the Progress demands a good draft. It's such an efficient stove, the flue is cool right out of the collar relative to other stoves I've had.

They make insulated liners for this purpose. Not much help if you already bought and paid for an uninsulated liner, but maybe useful info for the next guy searching this thread. I'm told these liners are the go-to standard for lining a masonry chimney in a very old house, where unknown or unidentified cumbustables may be adjacent to (or sometimes even running thru) the chimney.

If you wrap it you will have to pull it back out, if it wasn't hard to install that would be my choice. If you use a pour insulation make sure your block off plate is solid and make sure the mix is not to "soupy" as it will leak past the block off plate. Pour in insulation will be a bear to remove if you ever have to switch out your liner.

There is one Insulation mix on the market that claims "easy removal". It's a little pricey, though. I can't imagine why
I might want to pull the liner, but I guess you never know. Only reasons I could think are a) Chimney fire damages the liner b) switch to a 8" flue some day (nah, no Blaze King allowed in this house by the wife!) c) Need to "tweek" the height of the liner

Any other reasons I missed??

You can use rock wool also known as a Ceramic Wool Blanket. It can come with or without the foil and can be held in place by wrapping it with chicken wire. The other method is to fill the void around the liner with vermiculite.

Not sure what the wooley material is, but this is basically the construction of the insulated liner my stove shop supplies for houses with very old chimneys of unknown condition. Flex liner wrapped in insulation, foil, then wire.

From You can use rock wool also known as a Ceramic Wool Blanket. It can come with or without the foil and can be held in place by wrapping it with chicken wire. The other method is to fill the void around the liner with vermiculite.





I am reading an article about Vermiculite and it seems is Asbestos. If you put in your home, you can't sell it until the Asbestos is removed.

http://www.epa.gov/asbestos/pubs/verm.html

That would not be a smart move.


Robert

Interesting article. But it seems the vermiculite was contaminated by asbestos by a nearby mine, but it stopped production in 1990. I can't imagine 22 years later some of that old contaminated insulation is still in circulation, being sold??

Loose perlite works as well. I filled my 12x12 with it and the draft is great for a little on the short side 13' chimney.

Todd: Do you have a before and after comparison with that 12x12 flue? How did the same stove draft before insulating with the loose perlite? I just measured my liner, it's only about 15 feet from rear of stove to top of flue.

The Progress is difficult to start in warmer weather - just had a fire yesterday, 50F outside, 62 inside.

No before and after. When I busted out the old fireplace I installed the stove, liner and insulation all at the same time. But I can tell you it drafts just as well or sometimes seems better than my other Keystone that is hooked up to a 25' Supaflu. I think the insulation will only help your draft.

I wouldn't recommend anything with asbestos, even if you could get it. I'm not sure if all vermiculite has asbestos but the ceramic blanket would work best, otherwise a pour in material called TherMix is what's recommended in DuraVent's DuraFlex Pro guide as well as the foil backed cerramic blanket method.